Waves
And Wave Properties
Applied Physics and Chemistry SHM Lecture 2
Wave

A disturbance that transmits energy

Mechanical waves: require a medium to move

Transverse waves

Longitudinal waves
Transverse Wave


Movement
perpendicular to
direction of
wave
Example: light
Longitudinal Wave



Movement
parallel to
direction of wave
Series of
compressions
and rarefactions
Example: sound
Measuring the Wave

Speed: depends on the medium




Measured in m/s
Amplitude: maximum displacement from rest
Wavelength: distance between points where
wave pattern repeats
Frequency: number of waves that pass a point
in one second

Measured in Hertz (Hz): 1 Hz is one wave/second
Wave Equation

Relates frequency, velocity and wavelength

V=fλ


There is also a relationship between period and
frequency
T = 1/f
Sample Problem

A sound wave has a frequency of 192 Hz and
travels the length of a football field (91.4 m) in
0.271 s. What is the speed of the wave?

Known: f=192 Hz d=91.4 m t=0.271 s

Equation: V=d/t (no known λ)

Solve: V=(91.4m)/(0.271 s) = 337 m/s
Sample Problem Continued

Find the wavelength of the wave.

Known: V=337 m/s f=192 Hz

Equation V=fλ so λ=V/f

Solve: λ=(337 m/s)/192 Hz

So λ= 1.76 m
Sample Problem Continued

What is the period of the wave?

Known: f=192 Hz

Equation: T=1/f

Solve: T=1/192 Hz

T=0.00521 s
Sample Problem Continued

If the frequency was changed to 442 Hz, what
would the new wavelength be?

Known: V=337 m/s
f=442 Hz

Equation: V=fλ so λ=V/f

Solve: λ=(337 m/s)/(442 Hz)

And λ=0.762 m
Now you try it!

Solve the problems on your worksheet!
Remember the wave equation and the
relationship between period and frequency.